feat(MapKeys): Add MapKeys (#58)

* feat(MapKeys): Add MapKeys type * test(MapKeys): Add MapKeys type test * docs(MapKeys): Sort alphabetically * docs(MapKeys): Add MapKeys type documentation
haejunejung · Aug 29, 2024 · 41ecf7a · 41ecf7a
1 parent cec72c2
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Showing 8 changed files with 182 additions and 66 deletions.
diff --git a/docs/.vitepress/en.mts b/docs/.vitepress/en.mts
@@ -46,6 +46,43 @@ export default defineConfig({
               { text: 'Primitive', link: '/reference/basic/Primitive' },
             ],
           },
+          {
+            text: 'Map',
+            items: [{ text: 'MapKeys', link: '/reference/map/MapKeys' }],
+          },
+          {
+            text: 'Predicate',
+            items: [
+              { text: 'IsAny', link: '/reference/predicate/IsAny' },
+              { text: 'IsArray', link: '/reference/predicate/IsArray' },
+              { text: 'IsEqual', link: '/reference/predicate/IsEqual' },
+              { text: 'IsTuple', link: '/reference/predicate/IsTuple' },
+              { text: 'IsNever', link: '/reference/predicate/IsNever' },
+              { text: 'IsUnknown', link: '/reference/predicate/IsUnknown' },
+            ],
+          },
+          {
+            text: 'Special',
+            items: [{ text: 'Brand', link: '/reference/special/Brand' }],
+          },
+          {
+            text: 'String',
+            items: [
+              { text: 'Replace', link: '/reference/string/Replace' },
+              { text: 'ReplaceAll', link: '/reference/string/ReplaceAll' },
+              { text: 'Split', link: '/reference/string/Split' },
+              { text: 'WithPrefix', link: '/reference/string/WithPrefix' },
+            ],
+          },
+          {
+            text: 'URL Parser',
+            items: [
+              {
+                text: 'ExtractRouteParams',
+                link: '/reference/url-parser/ExtractRouteParams',
+              },
+            ],
+          },
           {
             text: 'Utilities',
             items: [
@@ -75,39 +112,6 @@ export default defineConfig({
               },
             ],
           },
-          {
-            text: 'String',
-            items: [
-              { text: 'Replace', link: '/reference/string/Replace' },
-              { text: 'ReplaceAll', link: '/reference/string/ReplaceAll' },
-              { text: 'Split', link: '/reference/string/Split' },
-              { text: 'WithPrefix', link: '/reference/string/WithPrefix' },
-            ],
-          },
-          {
-            text: 'Special',
-            items: [{ text: 'Brand', link: '/reference/special/Brand' }],
-          },
-          {
-            text: 'URL Parser',
-            items: [
-              {
-                text: 'ExtractRouteParams',
-                link: '/reference/url-parser/ExtractRouteParams',
-              },
-            ],
-          },
-          {
-            text: 'Predicate',
-            items: [
-              { text: 'IsAny', link: '/reference/predicate/IsAny' },
-              { text: 'IsArray', link: '/reference/predicate/IsArray' },
-              { text: 'IsEqual', link: '/reference/predicate/IsEqual' },
-              { text: 'IsTuple', link: '/reference/predicate/IsTuple' },
-              { text: 'IsNever', link: '/reference/predicate/IsNever' },
-              { text: 'IsUnknown', link: '/reference/predicate/IsUnknown' },
-            ],
-          },
         ],
       },
     ],

diff --git a/docs/.vitepress/ko.mts b/docs/.vitepress/ko.mts
@@ -49,6 +49,43 @@ export default defineConfig({
               { text: 'Primitive', link: '/ko/reference/basic/Primitive' },
             ],
           },
+          {
+            text: 'Map',
+            items: [{ text: 'MapKeys', link: '/ko/reference/map/MapKeys' }],
+          },
+          {
+            text: 'Predicate',
+            items: [
+              { text: 'IsAny', link: '/ko/reference/predicate/IsAny' },
+              { text: 'IsArray', link: '/ko/reference/predicate/IsArray' },
+              { text: 'IsEqual', link: '/ko/reference/predicate/IsEqual' },
+              { text: 'IsTuple', link: '/ko/reference/predicate/IsTuple' },
+              { text: 'IsNever', link: '/ko/reference/predicate/IsNever' },
+              { text: 'IsUnknown', link: '/ko/reference/predicate/IsUnknown' },
+            ],
+          },
+          {
+            text: 'Special',
+            items: [{ text: 'Brand', link: '/ko/reference/special/Brand' }],
+          },
+          {
+            text: 'String',
+            items: [
+              { text: 'Replace', link: '/ko/reference/string/Replace' },
+              { text: 'ReplaceAll', link: '/ko/reference/string/ReplaceAll' },
+              { text: 'Split', link: '/ko/reference/string/Split' },
+              { text: 'WithPrefix', link: '/ko/reference/string/WithPrefix' },
+            ],
+          },
+          {
+            text: 'URL Parser',
+            items: [
+              {
+                text: 'ExtractRouteParams',
+                link: '/ko/reference/url-parser/ExtractRouteParams',
+              },
+            ],
+          },
           {
             text: 'Utilities',
             items: [
@@ -78,39 +115,6 @@ export default defineConfig({
               },
             ],
           },
-          {
-            text: 'String',
-            items: [
-              { text: 'Replace', link: '/ko/reference/string/Replace' },
-              { text: 'ReplaceAll', link: '/ko/reference/string/ReplaceAll' },
-              { text: 'Split', link: '/ko/reference/string/Split' },
-              { text: 'WithPrefix', link: '/ko/reference/string/WithPrefix' },
-            ],
-          },
-          {
-            text: 'Special',
-            items: [{ text: 'Brand', link: '/ko/reference/special/Brand' }],
-          },
-          {
-            text: 'URL Parser',
-            items: [
-              {
-                text: 'ExtractRouteParams',
-                link: '/ko/reference/url-parser/ExtractRouteParams',
-              },
-            ],
-          },
-          {
-            text: 'Predicate',
-            items: [
-              { text: 'IsAny', link: '/ko/reference/predicate/IsAny' },
-              { text: 'IsArray', link: '/ko/reference/predicate/IsArray' },
-              { text: 'IsEqual', link: '/ko/reference/predicate/IsEqual' },
-              { text: 'IsTuple', link: '/ko/reference/predicate/IsTuple' },
-              { text: 'IsNever', link: '/ko/reference/predicate/IsNever' },
-              { text: 'IsUnknown', link: '/ko/reference/predicate/IsUnknown' },
-            ],
-          },
         ],
       },
     ],

diff --git a/docs/ko/reference/map/MapKeys.md b/docs/ko/reference/map/MapKeys.md
@@ -0,0 +1,32 @@
+# MapKeys\<T>
+
+## 개요
+
+주어진 Map 타입 `T`로 부터 키 타입을 추출해요.
+
+## 문법
+
+```ts
+type MapKeys<T extends Map<unknown, unknown>> =
+  T extends Map<infer K, unknown> ? K : never;
+```
+
+- **T**: 키 타입을 추출할 Map 타입이에요.
+
+## 예제
+
+```ts
+const phoneBook: Map<'tomas' | 'sha', string> = new Map([
+ ['tomas': '010-0000-0000'],
+ ['sha': '010-1111-1111'],
+])
+
+type PhoneBookKeys = MapKeys<typeof phoneBook>; // 'tomas' | 'sha'
+
+const hashMap: Map<string, string> = new Map([
+ ['0': 'coffee'],
+ ['1': 'dessert']
+])
+
+type HashMapKeys = MapKeys<typeof hashMap>; // string
+```
diff --git a/docs/reference/map/MapKeys.md b/docs/reference/map/MapKeys.md
@@ -0,0 +1,32 @@
+# MapKeys\<T>
+
+## Overview
+
+Extracts the key type from a given map type `T`.
+
+## Syntax
+
+```ts
+type MapKeys<T extends Map<unknown, unknown>> =
+  T extends Map<infer K, unknown> ? K : never;
+```
+
+- **T**: The map type from which to extract the key type.
+
+## Examples
+
+```ts
+const phoneBook: Map<'tomas' | 'sha', string> = new Map([
+ ['tomas': '010-0000-0000'],
+ ['sha': '010-1111-1111'],
+])
+
+type PhoneBookKeys = MapKeys<typeof phoneBook>; // 'tomas' | 'sha'
+
+const hashMap: Map<string, string> = new Map([
+ ['0': 'coffee'],
+ ['1': 'dessert']
+])
+
+type HashMapKeys = MapKeys<typeof hashMap>; // string
+```
diff --git a/source/index.ts b/source/index.ts
@@ -1,4 +1,5 @@
 export * from './basic';
+export * from './map';
 export * from './predicate';
 export * from './string';
 export * from './special';

diff --git a/source/map/MapKeys.d.ts b/source/map/MapKeys.d.ts
@@ -0,0 +1,24 @@
+/**
+ * @description - Extracts the key type from a given map type `T`.
+ *
+ * @template T - The map type from which to extract the key type.
+ *
+ * @returns - The key type of `T`.
+ *
+ * @example
+ * const phoneBook: Map<'tomas' | 'sha', string> = new Map([
+ *  ['tomas': '010-0000-0000'],
+ *  ['sha': '010-1111-1111'],
+ * ])
+ *
+ * type PhoneBookKeys = MapKeys<typeof phoneBook>; // 'tomas' | 'sha'
+ *
+ * const hashMap: Map<string, string> = new Map([
+ *  ['0': 'coffee'],
+ *  ['1': 'dessert']
+ * ])
+ *
+ * type HashMapKeys = MapKeys<typeof hashMap>; // string
+ */
+export type MapKeys<T extends Map<unknown, unknown>> =
+  T extends Map<infer K, unknown> ? K : never;
diff --git a/source/map/index.ts b/source/map/index.ts
@@ -0,0 +1 @@
+export type { MapKeys } from './MapKeys';
diff --git a/test-d/map/MapKeys.test-d.ts b/test-d/map/MapKeys.test-d.ts
@@ -0,0 +1,18 @@
+import { expectNever, expectType } from 'tsd';
+import { MapKeys } from '@/map';
+
+declare function mapKeys<T extends Map<unknown, unknown>>(): MapKeys<T>;
+
+// Should extract map keys correctly as 'tomas' | 'sha'.
+declare const phoneBook: Map<'tomas' | 'sha', string>;
+expectType<'tomas' | 'sha'>(mapKeys<typeof phoneBook>());
+
+// Should extract map keys correctly as string.
+declare const hashMap: Map<string, string>;
+expectType<string>(mapKeys<typeof hashMap>());
+
+// Should correctly infer `any` as the key type.
+expectType<any>(mapKeys<Map<any, string>>());
+
+// Should not extract any keys and handle `never` type appropriately.
+expectNever(mapKeys<Map<never, string>>());